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Biomedical subjects

J W Myrick

Publications and source records attributed to J W Myrick.

6 recordsLinked to original sources
PubMed1980

Semiautomated method for analysis of enteric-coated and plain coated diethylstilbestrol tablets.

A semiautomated fluorometric method for the analysis of enteric-coated and plain coated diethylstilbestrol tablets is presented. To eliminate interferences from tablet excipients, diethylstilbestrol is extracted into an organic solvent and then into a basic aqueous solution. After UV irradiation, a product of diethylstilbestsrol is formed from which a fluorophore is produced chemically. The fluorescence is measured at an excitation wavelength of 335 nm and an emission wavelength of 410 nm. The coefficient of variation measured for the semiautomated procedure was 0.59%. Assay results agreed well with the USP procedure for tablets containing greater than 1 mg of diethylstilbestrol. Tablet dyes and excipients interfered in the USP procedure, which yielded low results for tablets containing less than 1 mg of diethylstilbestrol. Standard recovery data and assays of tablet composites showed that dyes and other excipients do not interfere with semiautomated procedure.

Autoanalysis↗
PubMed1980

Scope of differential UV and differential fluorescence assays for phenothiazines: comparison with official methods.

Operational difficulties have been encountered with many of the official phenothiazine assay procedures in this laboratory. Although some difficulties were corrected, the procedures still lack specificity. Accordingly, the general scope of differential UV and differential fluorescence methods was investigated. These specific methods are facile, reproducible, and applicable to both composite and single-tablet assays.

Oxidation-Reduction↗
PubMed1978

Versatile kinetic-approach to analysis of dissolution data.

A new kinetically based dissolution equation is presented that considers dissolution of polydisperse systems and disintegrating solid dosage forms. The equation is applicable under sink as well as nonsink conditions and enables the specific dissolution rate parameter, the dispersion parameter, the disintegration lag time, and a newly introduced parameter, the dissolution availability, to be evaluated simultaneously and directly from percent of label claim dissolved versus time data. The equation showed excellent fit to dissolution data for aminophylline tablets. The kinetic significance of the estimated parameters of the equation is discussed. The method of analysis is compared to an approach employing an empirical equation based on a modified Weibull distribution function.

Aminophylline↗
PubMed1978

Substitution of n-heptane for ethyl ether in USP assay for chlorpromazine hydrochloride in tablets, injections, and sirups.

Peroxide levels above 0.0001% in the ethyl ether used in the USP XIX assay for chlorpromazine hydrochloride in tablets, sirups, and injections produce a distorted spectrophotometric curve in the 350--220 nm region. The use of peroxide-free ethyl ether or n-heptane avoids this problem. Recoveries of 91-100% are obtained with either of these reagents.

Chlorpromazine↗